Device for rotation about an axis of rotation to drive liquid flow within the device comprising a first element, a second element and the radially outer wall of a cavity define a detection chamber

ABSTRACT

A device configured for rotation about an axis of rotation to drive liquid flow within the device. The device includes a detection chamber having opposed first second ends and two optical features defining an optical path through the detection chamber, between the first and second ends. The detection chamber includes a first liquid inlet disposed at the first end on a first side of the optical path, a first liquid outlet disposed at the second end of the detection chamber on the first side of the optical path and a second liquid outlet disposed at the second end of the detection chamber on a second side of the optical path. The first side of the optical path is radially outwards of the second side of the optical path.

RELATED APPLICATIONS

The present application claims priority to Great Britain Application No.1617081.3 filed Oct. 7, 2016 and Portuguese Application No. 109663 filedOct. 7, 2016, each of which is hereby incorporated herein in itsentirety by reference.

FIELD OF THE DISCLOSURE

The present invention relates to the handling of liquids and, inparticular, to a detection chamber for use in obtaining an opticalmeasurement of liquid in the detection chamber.

BACKGROUND OF THE DISCLOSURE

Obtaining optical measurements (for example a light absorption,reflection or scattering measurement) of a liquid is a useful tool inmany applications. In particular, optical measurements may be used todetermine characteristics (absorbance, turbidity) of a sample or acomponent of a sample; or to monitor the kinetics of a reaction. Inorder for such measurements to be carried out, the liquid is placed in areceptacle and exposed to a light beam. Light which is transmittedthrough, the liquid is then analysed and characteristics of the liquidcan be determined based on this analysis. The analytical procedure mayinvolve single-point, multiple-point or time-resolved measurements.

Optical measurements are used in ‘point of care’ applications to analyseblood samples. A device is used to hold the sample relative to anoptical unit (for producing a light beam and detecting transmitted orreflected light to infer, for example, the light absorbed or scatteredby the liquid). Such devices may be microfluidic devices and/or may becentrifugal devices, such as ‘lab on a disc’ devices.

As well as obtaining an optical measurement of a liquid sample, such asa blood sample, it may be desirable to obtain a reference measurementalso, for example a measurement of a buffer or saline solution, forcomparison with the result obtained for the liquid sample. This canfacilitate correction of results for imperfections in the receptacle inwhich the liquid is held, the material through which the light beampasses before and/or after passing through the liquid under measurementand/or imperfections in the optical unit, for example. It may also beadvantageous to ascertain the optical properties of the reagents beingused, in particular when these reagents are stored dry in the device andreconstituted at the moment of testing. Such reference measurements mayenable the presence of substances in the sample which may interfere withthe optical signal used for detection to be taken into account.

SUMMARY OF THE INVENTION

Aspects of the disclosure are set out in the independent claims.Further, optional features of embodiments are set out in the dependentclaims.

In some aspects, there is provided a device for handling liquid. Thedevice is configured for rotation about an axis of rotation to driveliquid flow within the device. The device comprises a detection chamberwith a first end and a second end, the second end being opposed to thefirst end. The device further comprises two optical features, forexample two reflective surfaces or diffractive surfaces with or withoutadditional surfaces in between, defining an optical path through thedetection chamber, from one of the first and second ends of thedetection chamber to the other of the first and second ends of thedetection chamber. The detection chamber comprises a first liquid inletdisposed at the first end of the detection chamber on a first side ofthe optical path, a first liquid outlet disposed at the second end ofthe detection chamber on the first side of the optical path and a secondliquid outlet disposed at the second end of the detection chamber on asecond side of the optical path. The first side of the optical path isradially outwards of the second side of the optical path.

Advantageously, this structure facilitates the replacement of one liquidin the detection chamber with another liquid, for example a referenceliquid such as buffer solution, or different preparations of the sampleor different samples. In particular, the positioning of one liquidoutlet of the detection chamber on one side of the optical path andanother liquid outlet of the detection chamber on the other side of theoptical path facilitates the replacement of one liquid in the detectionchamber with another and results in flow lines facilitating liquidexchange.

One advantage of replacing one liquid in a detection chamber withanother liquid is that the same detection chamber can be used formeasurement of both the sample and the reference liquid or for differentsamples/preparations. Advantageously, taking both measurements in thesame chamber facilitates correction of the results for any imperfectionsin the detection chamber. Conversely, if one detection chamber was usedfor a reference measurement and a second, different chamber was used formeasurement of the sample, any differences in the geometries of the twochambers, the dimensions relative to the optical path, or anyimperfections in one chamber which are not present in the other couldinfluence the results.

As mentioned above, one side of the optical path is radially outwards ofthe other side of the optical path, relative to the axis of rotation.The optical path may be disposed in a direction which has a tangentialcomponent as well as a radial component and may be non-parallel to thedirection of action of the centrifugal force. In some embodiments, theoptical path may be aligned tangentially or substantially tangentiallyand may be aligned in a direction perpendicular or substantiallyperpendicular to the direction of centrifugal force. An advantage of aconfiguration in which the optical path is aligned in a directionperpendicular or substantially perpendicular to the direction ofcentrifugal force is that the optical path (and hence the detectionchamber) may have a smaller radial extent, i.e. a smaller extent along aradial direction in the device, for a given optical path length. Thismay be advantageous if other structures need to be implemented on thedevice. For example, the device may be disc-shaped or substantiallydisc-shaped and radial space on the disc may be limited.

In some embodiments, the device defines a plane containing the liquidhandling structures of the device and the optical path is within theplane. For example, the device may be disc-shaped or substantiallydisc-shaped and the optical path may be within the plane of the disc.The optical path may be parallel or substantially parallel to the planeof the device.

It should be understood that the term ‘optical path’ refers to the pathalong which a light beam travels when the device is in use. It may alsobe defined as a notional normal joining the first and second reflectivesurfaces. At least part of this optical path may be used to probe liquidor otherwise gas contained in a detection chamber disposed between theoptical features.

As mentioned above, the device is configured for rotation about an axisof rotation to drive liquid flow within the device. In some embodiments,the device comprises a feature which defines the axis of rotation andwhich is configured to be coupled to a rotational element to driverotation of the device. For example, the device may be disc-shaped andmay comprise a central hole defining the axis of rotation. The hole maybe configured to engage with a drive mechanism for driving rotation ofthe device.

As described above, the first liquid outlet and the first liquid inletof the detection chamber are disposed on a first side of the opticalpath and the second liquid outlet of the detection chamber is disposedon a second side of the optical path, the first side being radiallyoutwards of the second side. The liquid inlet and one of the liquidoutlets are on a side of the optical path which is radially outwards ofthe other side of the optical path, on which the other of the two liquidoutlets is disposed. By positioning the liquid inlet on a radially-outerside of the optical path, the chances of removing the first liquid fromthe volume through which the light beam passes and filling that volumeentirely (or at least substantially) with the second liquid is increasedbecause the volume is filled radially inwards. This helps to maintain aclear boundary between the first and second liquids and reduces themixing of the two liquids.

In some embodiments, one or both of the first liquid outlet and thefirst liquid inlet are disposed at a radially-outermost aspect of thedetection chamber.

In some embodiments the second liquid inlet is disposed at aradially-innermost aspect of the detection chamber.

In some embodiments, the device comprises a cavity and the detectionchamber is disposed within the cavity. For example, the cavity maycontain one or more elements, such as pillars extending between a floorand a ceiling of the cavity, which define the detection chamber withinthe cavity between them. For example, the cavity may be defined betweenaxially spaced surfaces, in which case the elements may be pillarsextending in an axial direction between the axially spaced surfaces todefine the detection chamber between facing surfaces of the pillars andthe axially spaced surfaces.

In some embodiments, the device comprises a first element disposed inthe cavity on a first side adjacent to the first end of the detectionchamber and a second element disposed in the cavity on a second sideadjacent to the second end of the detection chamber. Each of the twooptical features is disposed in a respective one of the first and secondelements. The detection chamber is thus disposed between the firstelement and the second element.

In some embodiments, the first and second optical features may eachcomprise an indent in the body of the device in the region of eachelement to form an angled wall for reflecting light from outside thedevice into a plane of the device and/or for reflecting light fromwithin a plane of the device back out of the plane of the device. Thereflective surface of the optical features may be reflective by virtueof the difference in refractive indices of air and of the material ofthe body or may be fully or partially silvered or have some otherreflective coating.

In some embodiments, the cavity comprises a second liquid inlet on thefirst side of the cavity and the second element has a first side facingthe first element and a second side opposed to the first side. A firstwall of the cavity adjacent to the second side of the second elementextends radially inwards of the second element. The second liquid inletis disposed radially inwards of the first wall and the first elementextends radially inwards of the second liquid inlet. Thus, the firstliquid inlet is defined by a gap between the first element and a wall ofthe cavity. In some embodiments, the first liquid outlet is defined by agap between the second element and a wall of the cavity and aradially-outer aspect of the second liquid outlet is defined by aradially-inner wall of the second element.

The second liquid inlet is disposed radially inwards of the first wallso that liquid is able to flow over (i.e. radially inwards of) thesecond element. The first element extends radially inwards of the secondliquid inlet so that on entering the cavity via the second liquid inlet,liquid flows radially outwards, around the first element, rather thanflowing radially inwards of the first element.

This structure provides a compact configuration for the detectionchamber which is also easy to manufacture.

As mentioned above, a first wall of the cavity adjacent to the secondside of the second element extends radially inwards of the secondelement. In some embodiments, a further wall of the cavity, extendingfrom a radially inner end of the first wall, extends away from thesecond element, either radially outwards from the first point or in acircumferential direction from the first point.

In some embodiments, the first wall of the cavity extends radiallyinwards of the second element to a crest. A further wall of the cavityextends radially outwards from the crest. This feature may otherwise bereferred to as an overflow. By positioning the overflow (crest) radiallyinwards of the second element (i.e. radially inwards of the secondliquid outlet), the overflow is radially inwards of both the first andsecond liquid outlets and as a result, liquid flows out of the detectionchamber via both of the first and second liquid outlets and then overthe overflow (crest). The first liquid outlet (which is radiallyoutwards of the second liquid outlet) is not favoured over the secondliquid outlet due to its radial position relative to that of the secondliquid outlet.

In some embodiments, the cavity comprises a second, radially-outer walland a portion of the second wall between the first and second elementsis radially inwards of a portion of the second wall facing the firstelement. In some embodiments, the portion of the second wall facing thefirst element may face a radially outer portion of the first element.The term ‘between’ as used with reference to this embodiment should beunderstood to mean circumferentially between, but not necessarily inbetween in a radial sense. The circumferential position of the portionof the second wall is between the respective circumferential positionsof the first and second elements. The radial position of the portion ofthe second wall may or may not be fall within the radial extent of thefirst and second elements.

Advantageously, this configuration has the effect that liquid is guidedinto the detection chamber in a radially inwards direction. Accordingly,liquid already present in the detection chamber (which is radiallyinwards) is displaced, rather than liquid simply flowing along aradially-outermost aspect of the detection chamber.

In some embodiments, the device comprises an inlet conduit incommunication with the second liquid inlet and the inlet conduit issloped radially inwards.

In some embodiments, there is provided a method of taking an opticalmeasurement of a liquid in a device as described herein. The methodcomprises rotating the device to cause at least a portion of a firstliquid to flow into the detection chamber via the first liquid inletand, as a result, at least a portion of a second liquid, which ispresent in the detection chamber, to flow out of the detection chambervia the first and second liquid outlets.

In some embodiments, there is provided a method of taking an opticalmeasurement of a liquid in a device as described herein. The methodcomprises rotating the device to cause at least a portion of a firstliquid to flow into the detection chamber via the first liquid inletand, as a result, at least a portion of a second liquid, which ispresent in the detection chamber, to flow out of the detection chambervia the first and second liquid outlets.

In some embodiments, the method comprises, prior to rotating the deviceto cause at least a portion of a first liquid to flow into the detectionchamber via the first liquid inlet and, as a result, at least a portionof a second liquid, which is present in the detection chamber, to flowout of the detection chamber via the first and second liquid outlets,obtaining a first optical measurement of the second liquid in thedetection chamber. The method also comprises, subsequent to rotating thedevice to cause at least a portion of a first liquid to flow into thedetection chamber via the first liquid inlet and, as a result, at leasta portion of a second liquid to flow out of the detection chamber viathe first and second liquid outlets, obtaining a second opticalmeasurement, of the first liquid in the detection chamber.

In some embodiments there is provided a liquid handling systemcomprising a motor, a device as described herein, an optical unit forobtaining an optical measurement of a liquid in the device and acontroller coupled to the motor to control rotation of the device. Thecontroller is configured to implement methods as described herein.

The first and second liquids can each be any liquid. Examples include ablood sample (whole or lysed blood), blood plasma, urine, serum,dilutions of the same, particle suspensions (e.g. latex beads,nanoparticles), reaction mixtures, saline solution or another buffer.

In some embodiments, the device is a microfluidic device. For theavoidance of doubt, the term “microfluidic” is referred to herein tomean devices having a fluidic element such as a reservoir or a channelwith at least one dimension below 1 mm. The device may be configured tohandle volumes of liquid on the scale of nanoliters to microliters. Somebut not necessarily all of the liquid handling structures on such adevice may be microfluidic. For example, a length of the detectionchamber may be approximately 1 cm. More specifically, a length of theoptical path through the liquid in the detection chamber may be 1 cm. Insome embodiments, a distance between the first reflective surface andthe second reflective surface, through the detection chamber, is 1 cm.In some embodiments, the distance between the first reflective surfaceand the second reflective surface, through the detection chamber, isgreater than or equal to 1 cm.

As used herein, the term ‘outlet’ should be understood to refer to anyfeature via which liquid leaves a chamber or area of the device 2. Forexample, an outlet could be an opening in a wall of a chamber or cavity,an opening or gap between two pillars, an opening or gap between anelement or a pillar and a wall of a cavity or chamber or a connectionbetween a conduit or channel and a chamber or cavity. The term “conduit”used herein can thus be understood accordingly as being configured toprovide any suitable passage for liquid to an inlet or from an outlet,for example a channel, a space between features, such as walls, pillars,elements, etc., in accordance with various embodiments described herein.

As used herein, the term ‘pillar’ refers to a column which extendsbetween the top and bottom of a chamber or cavity. For example, inembodiments in which the device is disc-shaped or substantiallydisc-shaped, the pillar may extend between the top and bottom of achamber or cavity, perpendicular to the plane of the disc, in whichliquid flows.

It will be understood that reference to a structure ‘A’ being disposedradially inwards of a structure ‘B’ should be taken to mean that adistance between structure ‘A’ and the axis of rotation of the device isless than a distance between structure ‘B’ and the axis of rotation ofthe device.

Equally, it will be understood that, reference to a structure ‘A’ beingdisposed radially outwards of a structure ‘B’ should be taken to meanthat a distance between structure ‘A’ and the axis of rotation of thedevice is greater than a distance between structure ‘B’ and the axis ofrotation of the device.

It will be understood that reference to a structure extending radiallyinwards should be taken to mean that the structure extends towards theaxis of rotation. Equally, it will be understood that reference to astructure extending radially outwards should be taken to mean that thestructure extends away from the axis of rotation

BRIEF DESCRIPTION OF THE FIGURES

The following description of specific embodiments is made by way ofexample and illustration and not limitation, with reference to thedrawings in which:

FIG. 1A illustrates schematically a device comprising a detectionchamber;

FIG. 1B illustrates schematically the device of FIG. 1A;

FIG. 1C illustrates schematically the device of FIG. 1A;

FIG. 2 illustrates schematically a drive system configured for use witha device as described herein;

FIG. 3 illustrates schematically a further embodiment of a detectionchamber;

FIG. 4 illustrates an implementation of the structure illustratedschematically in FIG. 3;

FIG. 5 illustrates another implementation with two detection chambers asdescribed herein.

With reference to FIG. 1A, a liquid handling device 2 comprises adetection chamber 6 with a first end and a second end. The second end ofthe detection chamber 6 is opposed to the first end. An inlet conduit 4,for example a channel or other passage, is connected to the detectionchamber 6 via a first liquid inlet 8 of the detection chamber 6. Thefirst liquid inlet 8 is disposed at a radially-outermost aspect of thedetection chamber 6, at the first end of the detection chamber. Thedevice further comprises a first optical feature comprising a reflectivesurface 10 at the first end of the detection chamber and a secondoptical feature comprising a reflective surface 12 at the second end ofthe detection chamber. The first reflective surface 10 is configured todirect a light beam which is incident upon the first reflective surface10 from outside the device 2 towards the second reflective surface 12.The second reflective surface 12 is configured to direct a light beamwhich is incident upon the second reflective surface 12 from the firstreflective surface 10 back out of the device 2. The first and secondreflective surfaces define an optical path 14 through the detectionchamber 6. The optical path 14 is, of course, part of a longer opticalpath from a light source to the optical feature, from one of the opticalfeatures to the other, possibly through the device before and after theoptical feature, and back to a light detector. This has not beenillustrated in the drawings for the sake of clarity.

In some embodiments in which the device comprises a body, for example apolycarbonate body, in which the various features are formed, forexample in the shape of a disk, the full optical path startssubstantially at an emitter, travels through air, enters the disk at anangle as close as possible to the normal to the disk plane so as toavoid deflection as light enters the disk, travels inside thepolycarbonate until finding an inclined surface at 45 degrees at which,due to the refractive index difference between the plastic and air onthe other side of the 45 degree surface, the light beam is totalinternally reflected in the disk plane. Light continues to travel in theplastic until the first wall of the detection chamber (which may be awall substantially parallel to the axis of rotation or substantiallynormal to the disk to avoid deflection at the interface and may beoptically flat), enters the detection chamber and travels through theliquid (or air if the chamber is empty) and exits the detection chamberthrough the opposite wall (which, again, may be vertical, i.e.substantially parallel to the axis of rotation, and optically flat),travels through the plastic until the second 45 degrees inclined surfacedeflects the light so that it travels though the thickness of disk andexits the disk, finally travelling through air to the detector.

The detection chamber 6 further comprises a first liquid outlet 15 whichis connected to a first liquid outlet conduit 16 for example a channelor other passage. The first liquid outlet 15 is disposed at aradially-outermost aspect of the detection chamber 6, at the second endof the detection chamber.

The detection chamber 6 further comprises a second liquid outlet 22disposed at the second end of the detection chamber. The second liquidoutlet 22 is connected to a second liquid outlet conduit 24, for examplea channel or other passage. The second liquid outlet conduit 24 isconnected to the first liquid outlet conduit 16 and the two outletconduits (16 and 24) combine to form a common conduit 25. The commonconduit 25 is connected to a downstream liquid handling structure 18 viaan inlet 20. The inlet 20 of the downstream liquid handling structure 18is radially inwards of the second liquid outlet 22. In some embodiments,the second liquid outlet 22 may be disposed at a radially-innermostaspect of the detection chamber.

The device 2 further comprises an air conduit 26 for example a channelor other passage allowing the exchange of air, which connects thedetection chamber and the downstream liquid handling structure 18. Theair conduit 26 is connected to the detection chamber 6 at aradially-innermost aspect of the detection chamber and to the downstreamliquid handling structure 18 at a radially-innermost aspect of thedownstream liquid handling structure 18. The air conduit 26 isconfigured to allow air which is displaced by the flow of liquid fromthe detection chamber 6 to the downstream liquid handling structure 18to escape back into the detection chamber 6 and may be in communicationwith the atmosphere outside the device or an internal air circuit of thedevice.

The device 2 is configured to be rotated about an axis of rotation 28 inorder to impart a centrifugal force on liquid in the device 2 in orderto cause it to flow through the device 2. The direction of the resultingcentrifugal force is illustrated by arrow 30. In that sense, it will beunderstood that FIGS. 1A to 1C, and FIG. 3 below, can be seen as aschematic and/or developed view.

In some embodiments, the device 2 comprises a feature which defines theaxis of rotation and this feature is configured to engage with a drivingmechanism for driving rotation of the device. For example, the device 2may be disc-shaped and may comprise a central hole defining the axis ofrotation. The hole may be configured to engage with a drive mechanismfor driving rotation of the device.

The structure may also be described in terms of the flow paths into andout of the detection chamber. A first flow path into the detectionchamber 6 via the first liquid inlet 8 joins the detection chamber 6 ata first end of the detection chamber and at a radially-outermost aspectof the detection chamber. A first flow path out of the detection chamber6, via the first liquid outlet 15, is connected to the detection chamberat a second end of the detection chamber and at a radially-outermostaspect of the detection chamber. A second flow path out of the detectionchamber 6 via the second liquid outlet 22 is connected to the detectionchamber at the second end of the detection chamber. The second flow pathmay be connected to the detection chamber at a radially-innermost aspectof the detection chamber.

With reference to FIG. 2, a system 62 for driving liquid flows in thedevice 2 and for taking optical measurements of liquid in the variousdetection chambers of the device 2 in accordance with the embodimentsdescribed above comprises a device engaging feature 64, for example aspindle with spring-loaded prongs for engaging a corresponding featureof the device, a tray and hub arrangement or any other arrangement forengaging the device 2, for example as commonly found in CD or DVDdrives. The engaging feature 64 is coupled to an electric motor 70 whichis controlled by a controller 66 configured to implement rotationalspeed protocols to drive liquid flows as described above.

The controller 66 is also coupled to and controls optical measurementunit 68 which is configured to generate a light beam and direct thelight beam towards the device 2 and, in particular, to one of theoptical features in the device 2. The optical measurement unit 68 isalso configured to receive the light beam reflected back from the deviceand to measure the intensity of the light.

Another embodiment of a detection chamber as described herein is shownschematically in FIG. 3. The embodiment is similar to that shown in FIG.1A in a number of ways. In the embodiment illustrated in FIG. 3, thevarious inlets and outlets and inlet and outlet conduits of theembodiment shown in FIG. 1 are formed by a cavity containing twoelements, as will now be described. The cavity may be defined betweenaxially spaced surfaces of the device (i.e., spaced along the axis 28),which can be pictured parallel to the plane of the drawings in FIG. 3and the elements may extend like pillars between the axially spacedsurfaces. For the sake of ease of description, these elements will bereferred to as pillars below. Accordingly, a number of the features ofthe structure shown in FIG. 1A are also present in that shown in FIG. 3.Like parts are labelled with like reference numerals and a descriptionof these parts will not be repeated.

In the embodiment shown in FIG. 3, the detection chamber 6 is disposedwithin a cavity 32. The cavity 32 comprises an inlet 44, which isconnected to an inlet conduit 46. A first pillar 34 is disposed withinthe cavity 32 on first side of the cavity 32 and a second pillar 36 isdisposed within the cavity 32 on a second side of the cavity 32. Thesecond pillar 36 has a first side 39, which faces the first pillar 34,and a second side 41 which is opposed to the first side of the secondpillar. The first reflective surface 10 is disposed within the firstpillar 34 and the second reflective surface 12 is disposed within thesecond pillar 36.

A wall of the first pillar 34 and a first side wall 32 a of the cavity32 define the inlet conduit 4, which is in communication with the firstliquid inlet 8 of the detection chamber. The first liquid inlet 8 isprovided by a space or passage between the first pillar 34 and a secondside wall 32 b of the cavity 32.

A wall 41 of the second pillar 36 and a third side wall 37 of the cavity32 define the first liquid outlet conduit 16, which is in communicationwith the first liquid outlet 15 of the detection chamber 6. The firstliquid outlet 15 provided by a space or passage between the secondpillar 36 and the second side wall 32 b of the cavity 32.

The second liquid outlet 22 of the detection chamber 6 is adjacent to aradially inner wall 23 of the second pillar 36. In particular, aradially-inner aspect of the second liquid outlet 22 is provided by theradially inner wall 23 of the second pillar 36. In this way, theradially inner wall 23 of the second pillar 36 provides an overflowstructure over which, in use, liquid flows.

The first pillar 34 extends radially inwards of the second pillar 36. Inthe embodiment shown in FIG. 3, a radially-inner wall 35 of the firstpillar 34 is disposed radially inwards of a radially-inner wall 23 ofthe second pillar 36. The first pillar 34 also extends radially inwardsof the liquid inlet 44 of the cavity 32.

The third side wall 37 of the cavity 32 adjacent to the second side 41of the second pillar 36 extends radially inwards of the second pillar36. The third side wall 37 extends radially inwards to a crest 33. Afifth side wall 38 of the cavity 32 extends from the crest 33 radiallyoutwards. In this way, the wall of the cavity forms an overflowstructure, over which any liquid radially inwards of the crest 33 flowsover the crest. The crest 33 is disposed radially inwards of the secondpillar 36.

The downstream liquid handling structure 18 is defined by further sidewalls of the cavity 32.

This structure may also be described in terms of the flow paths into andout of the detection chamber, as follows.

Two walls of the first pillar 34 and the first and second side walls 32a,b of the cavity 32 define a flow path into the detection chamber 6 viathe liquid inlet 8. In particular, first and second side walls 32 a,band the walls of the first pillar 34 define a channel along which liquidflows into the detection chamber 6. The flow path into the detectionchamber 6 extends around the first pillar 34, radially outwards of thefirst pillar. The respective walls of the cavity 32 and first pillar 34may be parallel or substantially parallel. In some embodiments, aportion of the first flow path into the detection chamber upstream ofthe first liquid inlet is radially outwards of the first liquid inlet.

The third and second side walls 37, 32 b of the cavity 32 and two wallsof the second pillar 36 define a first flow path out of the detectionchamber 6 via the first liquid outlet 15, around the second pillar,radially outwards of the second pillar 36. In particular, the third andsecond walls of the cavity 32 and two walls of the second pillar 36define a passage along which liquid flows out of the detection chamber6. The respective walls may be parallel or substantially parallel. Insome embodiments, the first flow path extends radially outwards from thefirst liquid outlet 15.

A radially inner wall 36 a of the second pillar 36 defines a second flowpath out of the detection chamber 6 via the second liquid outlet 22. Thesecond flow path extends around the second pillar 36, radially inwardsof the second pillar. A radially-inner side of the second pillar 36 thusmay form an overflow structure. In use, liquid flows over the secondpillar 36, out of the detection chamber 6.

The first and second flow paths (via the first and second liquid outletsrespectively) combine, traverse the crest 33 and pass into thedownstream liquid handling structure 18.

An implementation of the structure shown schematically in FIG. 3 isillustrated in FIG. 4. Like parts are labelled with like referencenumerals and these will not be described again here. Some additionalfeatures of the structure shown in FIG. 4 as compared to that shown inFIG. 3 and some features of the structure worth highlighting are asfollows:

-   -   The device 2 comprises a third pillar 38 in the cavity 32 to        provide structural support in the cavity 32.    -   The first liquid inlet 8 is disposed at a radially-outermost        aspect of the detection chamber 6. The inlet conduit 4 extends        radially inwards to the first liquid inlet 8. A portion 29 of        the second wall 32 b wall between the first and second pillars        is radially inwards of a portion of the second wall 32 b facing        the first pillar. Advantageously, this configuration has the        effect that liquid is guided into the detection chamber in a        radially inwards direction. Accordingly, liquid already present        in the detection chamber (which is radially inwards) is        displaced, rather than liquid simply flowing along a        radially-outermost aspect of the detection chamber.    -   The first liquid outlet 15 is disposed at a radially-outermost        aspect of the detection chamber 6. The first liquid outlet        conduit 16 extends radially-outward from the first liquid outlet        15. Advantageously, this facilitates the effective removal of a        first liquid in the detection chamber from the detection chamber        and its replacement with a second liquid. The first liquid        outlet conduit 16 extends radially-outward from the first liquid        outlet 15 and then radially inwards, around the second pillar        36.    -   A fourth pillar 42 is disposed within the downstream liquid        handling structure 18 in order to provide structural support in        the downstream liquid handling structure.

With reference to FIG. 5, another implementation of the structure shownschematically in FIG. 1A is described. In this embodiment, a firstdetection unit 48, which comprises the detection chamber 6, the first,second and third pillars 34, 36 and 38 the inlet conduit 4 and theoutlet conduits 16 and 24, is connected to another such detection unit50. This second detection unit 50 is in turn connected to a downstreamliquid handling structure 18 (as described above), in which threepillars 52, 54 and 56 are disposed in order to provide structuralsupport.

The detection chamber and related conduits have been described above,with reference to FIGS. 3, 4 and 5, as defined by certain side walls ofthe cavity 32 and walls of the pillars 35 and 36. It will, of course, beunderstood that the axially spaced walls of the cavity 32 also definethe detection chamber there between.

Liquid flows in the device 2 and the corresponding method steps will nowbe described with reference to FIGS. 1B, 1C, 3 and 4.

With reference to FIG. 1B, as a preliminary step, the device 2 isrotated in order to cause a first liquid 58 to enter the detectionchamber 6 via the first liquid inlet 8. In some embodiments, the firstliquid 58 may already be present in the detection chamber 6 and thepreliminary step of causing the first liquid to enter the detectionchamber 6 may be omitted.

An optical measurement of the first liquid 58 in the detection chamber 6is then taken. An optical measuring unit may be used to produce a lightbeam and direct the light beam onto the first reflective surface 10. Thelight beam is then directed by the first reflective surface 10 throughthe detection chamber 6 (and hence through the liquid 58 in thedetection chamber) towards the second reflective surface 12. The secondreflective surface 12 then directs the light beam back out of the device2, where it is measured.

With reference to FIG. 1C, the device 2 is then rotated again (orrotation is continued) in order to cause a second liquid 60 to enter thedetection chamber 6 via the first liquid inlet 8. In doing so, at leasta portion of the first liquid 58 is forced out of the detection chamber6 via the first and second liquid outlets 15 and 22 and into thedownstream liquid handling structure 18. In some embodiments, all orsubstantially all of the first liquid 58 is forced out of the detectionchamber 6 and into the downstream liquid handling structure 18. Bypositioning the outlets of the detection chamber one either side of theoptical path 14, the chance that, after rotating to cause the secondliquid to enter the detection chamber 6, the volume of the detectionchamber through which the light beam passes will be entirely filled withthe second liquid 60 is increased, the first liquid 58 having beenforced out of the volume by the arrival of the second liquid 60.

An optical measurement of the second liquid 60 in the detection chamber6 is then taken, in line with the method described above.

Liquid flows within the device shown in FIG. 4 are now described. Thedevice 2 is rotated in order to cause a first liquid to enter the cavity32 via inlet conduit 46 and inlet 44. Liquid flows into the first inletconduit 4 and subsequently into the detection chamber 6 via the firstliquid inlet 8. Under the action of centrifugal force, the detectionchamber 6 fills with liquid. The device 2 is then stopped and a firstoptical measurement of the first liquid in the detection chamber 6 istaken.

The device 2 is then rotated again in order to cause a second liquid toenter the cavity 32 via the inlet conduit 46 and the inlet 44. Thesecond liquid flows into the first inlet conduit 4 and as it does so,the second liquid displaces the first liquid and forces it along theconduit. The second liquid subsequently enters the detection chamber 6via the first liquid inlet 8. The detection chamber 6 fills with thesecond liquid and as this happens, the first liquid in the detectionchamber is displaced and forced out of the detection chamber 6 via thefirst and second liquid outlets 15 and 22. Liquid then overflows intothe downstream liquid handling structure 18. A second opticalmeasurement of the second liquid in the detection chamber 6 is thentaken.

In the embodiment shown in FIG. 5, instead of liquid overflowing fromthe detection chamber 6 into the downstream liquid handling structure18, liquid overflows into the second detection unit 50. The first liquidenters and fills the detection chamber of the second unit 50 in the sameway as described for the first detection unit 48, with reference to FIG.4. Meanwhile, the second liquid 60 fills the detection chamber 6 of thefirst unit 48 as described above. An optical measurement of the firstliquid in the detection chamber of the second detection unit 50 and anoptical measurement of the second liquid in the detection chamber 6 ofthe first unit 48 is then taken.

The device 2 can then be rotated again in order to cause a third liquidto enter the cavity 32 via the inlet conduit 46 and the inlet 44. Thisdisplaces the second liquid from the first unit 48 into the second unit50, which in turn displaces the first liquid from the second unit 50into the downstream liquid handling structures. In this way, a series ofliquids can be caused to flow through the first and second units 48 and50 and a number of optical measurements of the various liquids in thevarious detection chambers taken.

In some embodiments, the device 2 may comprise any number of detectionunits, such as units 48 and 50, connected in sequence.

The above description has been made in terms of specific embodiments forthe purpose of illustration and not limitation. Many modifications andcombinations of, and alternatives to, the features described above willbe apparent to a person skilled in the art and are intended to fallwithin the scope of the invention, which is defined by the claims thatfollow.

For example, while conduits have been described above with reference todrawings depicting channel shaped conduits, it will be understood thatthe term “conduit” covers any arrangement providing a flow pathconveying or conducting liquid from one part of the device to another.It will also be understood that the term “chamber” covers anyarrangement which can contain liquid.

A cavity will be understood to be an empty space inside the device inwhich fluid can be contained or guided. An example of a cavity is achamber.

The liquid handling structures in a device as described herein, such asthe cavities, chamber and channels, are moulded or stamped in asubstrate (which may otherwise be referred to as a carrier disc). Acover foil is then attached to the substrate to form the chambers andother structures. Equally, two discs may be joined together to form theliquid handling structures.

Specific embodiments have been described in which optical features usedto direct light are provided in the form of reflective surfaces, forexample based on total internal reflection or reflective coatings.Equally, the optical features may be provided by diffractive gratings todirect a diffraction order through the detection chamber. Likewise,while the optical path has been illustrated as a straight line betweenthe optical features, the optical features may instead be configuredsuch that light is directed through the detection chambers at an angle,for example to reflect one or more times from axially spaced walls ofthe detection chamber in between the optical features.

Where methods have been described above that require control of a drivesystem, the control steps may be implemented in software, hardware or acombination thereof, and may involve a single hardware component such asa general purpose processor or application specific integrated circuitor distributed in any way between a number of processors and integratedcircuits. The components of the drive system may be provided in a singledevice or may be distributed in any suitable manner between a number ofdevices.

The invention claimed is:
 1. A device for handling liquid, the devicebeing configured for rotation about an axis of rotation to drive liquidflow within the device, the device comprising: a cavity; a liquid inletinto the cavity; a first element disposed in the cavity adjacent theliquid inlet and comprising a first optical element; a second elementdisposed in the cavity spaced from the first element and comprising asecond optical element, wherein the first element, second element and aradially outer wall of the cavity define a detection chamber; the firstand second optical elements define an optical path through the detectionchamber there-between; a gap between the first element and the radiallyouter wall of the cavity defines a liquid inlet into the detectionchamber; a gap between the second element and the radially outer wall ofthe cavity defines a liquid outlet from the detection chamber; aradially inner surface of the second element defines an overflow fromthe detection chamber; a radially inwards extending wall of the cavityadjacent the second element extends radially inward of the secondelement to define a flow path from the liquid outlet around the secondelement; the liquid inlet into the cavity is disposed radially inwardsof the radially inwards extending wall; and the first element extendsradially inwards of the liquid inlet into the cavity to define a liquidinlet conduit between the liquid inlet into the cavity and the liquidinlet into the detection chamber.
 2. A device as claimed in claim 1,wherein a direction between the first and second elements is alignedsubstantially tangentially relative to the axis of rotation.
 3. A deviceas claimed in claim 1, wherein the device comprises a feature whichdefines the axis of rotation and which is configured to be coupled to arotational element to drive rotation of the device.
 4. A device asclaimed in claim 1, wherein a portion of the radially outer wall betweenthe first and second elements is radially inwards of a portion of theradially outer wall facing the first element.